One of the great musical bummers of our time has been the wholesale narrowing of the phrase "dance music." In modern-day parlance, it's come to signify mostly the thump-based electronic beats created on computer and delivered by DJs in sweaty EDM clubs.

But on Halloween night in Hollywood while zombies, sexy nurses, skateboarding skeletons, Waldos, Mario Bros., little lambs and murder victims wandered Sunset Boulevard, a masked rock band called the Reflektors spun the legendary dance floor of the Hollywood Palladium by reawakening body music for the head-nodding guitar crowd.

Otherwise known as Arcade Fire, the moniker by which the Grammy-winning Canadian band made its name, the masquerading Reflektors shook the building with jumbo grooves that drove amazing moves. The frenzied rhythm track "Here Comes the Night Time" spawned particularly wild maneuvers as a grand mirror ball hung above, sparking the nether regions of a fan base known more for chorus-screaming than butt shaking.

People danced, bumped elbows, spilled drinks on shoulders (ahem) and sweated hard at the Palladium. By the end of the set the place reeked of alcohol, weed, perspiration and perfume.

But then, there was reason to party. Arcade Fire's highly anticipated fourth album, "Reflektor," was released this week to rave reviews, and the band had been camped in the neighborhood over the past days for a series of shows. At the Capitol Records building a few blocks away it holed up for a Capitol Studios session broadcast on NPR, and a night later it gigged an outdoor concert nearby for a select group of fans -- and "Jimmy Kimmel Live" viewers.

This Palladium set was the biggest of the run yet, and the band ripped through a set list heavy on the new work, with a couple glimpses back. One of the latter, its cover of Devo's "Uncontrollable Urge," hit like a water balloon, with vocalist Win Butler, wearing a huge papier-mache head, doing his best Mark Mothersbaugh impersonation. He tapped the side of his noggin and ranted of "an uncontrollable urge -- I want to scream and shout it!" Butler also alluded to the passing of Lou Reed with an impromptu run through a few lines of the Velvet Underground's "Beginning to See the Light."

By that late point the crowd was totally lubricated. The band had set a propulsive pace from the initial kick drum of its first song, the seven-minute title track. A deep, unapologetic disco-inspired sprint featuring bold breaks and New York club banging tones, its rhythm echoed while fans chanted the chorus.

With a live lineup now featuring two Haitian-based percussionists, Arcade Fire circa 2013 is more rhythm oriented, but seldom at the expense of structure. In fact, for all of the emphasis on beats and measures, new songs such as “You Already Know,” “Normal Person” and “Joan of Arc” peaked when guitars and drums collided. Ditto the few old songs performed. “Neighborhood #3 (Power Out),” from the first album, seemed boldfaced, denser with texture and color.

The band closed with the Régine Chassagne-sung “Haiti” and “Sprawl II (Mountains Beyond Mountains),” both of which served as a reminder that so-called “dance music” ideas have been there all along. Little did we know how much of a portent these tracks were, though, and how vivid they could be within a new context.

It was as though the songs, like the band, were less restrained due to the anonymity of the masks. Stripped of the burden of being Grammy winners, the group let loose a sound that blossomed as body music, and the crowd's response reflected this.

By the end of the night, the Reflektors had confirmed that the battle for world’s most explosive rock/dance/rhythm band has gotten a little more interesting. Which is to say: Arcade Fire had better watch its back.

In case you’ve been lost at sea and starved of Instagram, Twitter and potable drinking water for the last six months, the Arcade Fire have a new album out Tuesday called "Reflektor." A few years in the making and mostly produced by the band with James Murphy (LCD Soundsystem, DFA) and...